Numerous injection devices are available for the administration of various medical, pharmaceutical and cosmetic fluid products, including, for example, administration of insulin, and growth hormones. Such injection devices include so-called injection pens (or pen injectors) which are generally shaped and configured like a large pen and are conventionally utilized for self-administered injections. Injection pens may comprise a casing or housing in which is disposed the fluid to be administered. Such fluid is often contained in a second housing, such as a carpoule (also referred to as an ampoule), which may be removable and replaceable with respect to the injector housing. An injection needle or cannula may be placed in communication with the fluid product and configured to deliver the fluid product therethrough upon actuation of the injection device. The injection device may additionally include various mechanisms disposed within the injector housing which enable the administration of the fluid product through the needle in accordance with one or more specified requirements.
For example, a known mechanism for dispensing the fluid product from the container includes a manually deployed actuator that causes displacement of the fluid product from its associated container through the associated needle. Additionally, many injection devices include a mechanism for user adjustment of the dosage or volume of material which is to be delivered through the needle upon deployment of the dispensing actuator. In other injection devices, the dosage may be pre-set or predetermined such that a consistent volume of fluid product is dispensed each time the dispensing actuator is deployed or triggered. A mechanism may be configured to indicate, for example, a selected dosage, a cumulative total of fluid product which has been dispensed from a given container, or a residual amount of the product still remaining in the container. A conventional injection device which includes some of the above listed features is disclosed in U.S. Pat. No. 5,279,586 to Balkwill.
Many conventional injection devices, including those disclosed by the Balkwill patent, have manual actuating mechanisms that require displacement thereof in a direction that is collinear with a longitudinal axis of the injection device's housing. In other words, the actuator is often disposed at an end of the injection device opposite the needle or cannula and must be displaced in a direction towards the needle or cannula in order to effect dispensing of a fluid product. Thus, in operation, such conventional devices are often grasped in the palm of a user's hand with the user's fingers wrapping therearound to form a fist. The user may then position the injection device so as to insert the needle into the user's skin in anticipation of delivering the fluid product. The actuator of the device is then displaced by application of force thereto by a user's thumb. Alternatively, a user may grasp such an injection device between his or her thumb and at least one finger, such as their middle finger, and then displace the actuator with his or her forefinger. In either case, the displacement of the actuator at the end of the injection device can be awkward and difficult for many individuals.
For example, elderly individuals or individuals with impaired hand function may lack the dexterity, motor skills, strength, or a combination thereof, to actuate the injection device while maintaining a firm grasp. Thus, individuals with arthritis or some other ailment affecting the use of their hands may have considerable difficulty in administering therapeutic injections. Ultimately, the difficulty in administering such injections may result in noncompliance by a user with regard to the regular administration of injections in accordance with a prescribed treatment.
Another injection device which employs a different actuation mechanism configuration is disclosed in U.S. Pat. No. 5,584,815 to Pawelka et al. The Pawelka patent generally discloses an injection device having a wing member extendable from one side, wherein pivotal displacement of the wing actuates a dispensing mechanism for delivery of a fluid product through its associated needle and also resets a dosage indicator to an initial zero position. Thus, in operation, a user clasps the circumference of the injection apparatus and pushes the wing into the interior of the apparatus, such that it is angularly displaced about a pivot or fulcrum point.
However, the device disclosed in the Pawelka patent may be prone to an inadvertent discharge or dispensing of fluid during the act of inserting the needle into a user's skin. For example, since the fulcrum of wing actuator is designed such that a user's hand will be positioned between the fulcrum of the wing and the needle during operation, a user may inadvertently displace the wing while grasping the injection device and applying a force in the direction of the needle, as is required to insert the needle into the user's skin. Thus, the user of the device may not receive the proper amount of fluid during the injection, as some fluid become lost during the inadvertent displacement of the wing. While it is recognized that a user may position their hand at a different location during insertion of the needle and then reposition their hand after such insertion, such a process may be laborious and difficult for those with poor motor skills or those that exhibit impaired hand function.
In view of the shortcomings in the art, it would be advantageous to provide a method and device which enables individuals with poor motor skills or with impaired hand function to consistently administer injections in a safe, simple, and accurate manner. It would further be desirable to provide such a method and device which minimize the number of actions required by the user and simplifies the injection process.